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Commit 9f264be6 authored by Paul Mackerras's avatar Paul Mackerras
Browse files

[POWERPC] Optimize fls64() on 64-bit processors 



64-bit powerpc processors can find the leftmost 1 bit in a 64-bit
doubleword in one instruction, so use that rather than using the
generic fls64(), which does two 32-bit fls() calls.

Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 945feb17

include/asm-powerpc/bitops.h

+17 −0
Original line number Diff line number Diff line
@@ -312,7 +312,24 @@ static __inline__ int fls(unsigned int x) 
	asm ("cntlzw %0,%1" : "=r" (lz) : "r" (x));

	return 32 - lz;

}



/*

 * 64-bit can do this using one cntlzd (count leading zeroes doubleword)

 * instruction; for 32-bit we use the generic version, which does two

 * 32-bit fls calls.

 */

#ifdef __powerpc64__

static __inline__ int fls64(__u64 x)

{

	int lz;



	asm ("cntlzd %0,%1" : "=r" (lz) : "r" (x));

	return 64 - lz;

}

#else

#include <asm-generic/bitops/fls64.h>

#endif /* __powerpc64__ */



#include <asm-generic/bitops/hweight.h>

#include <asm-generic/bitops/find.h>